This invention relates to a flaw detection system, and more particularly to a flaw detection system of the type which utilizes a light collector rod means for applying light from the material being examined to a suitable detector. This invention is more particularly concerned with the means for aligning the light collector rod means with the scanning light beam of the flaw detection system.
Flaw detection systems have been developed in which a light source is successively scanned across a web or sheet of moving material being examined, in order to determine if any flaws exist therein. The light applied to the material is either transmitted, reflected, or scattered, and if a detector is employed to detect such radiation, any change from the normal pattern of reflected, transmitted, or scattered light is one means of determining whether a flaw exists in the material. In order for the system to function properly, the scanning light beam must be continually imaged on the detector as the light beam scans the material, so the variations in the light pattern may be picked up and detected by the detector. Improper alignment would defeat the purpose of the system. In systems such as that shown and described in patent application Ser. No. 449,247, filed Mar. 8, 1974, now U.S. Pat. No. 3,900,625, a folddown optical mirror and light source is utilized for providing the alignment function. This alignment means is perfectly adequate for the type of receiver which is shown in the aforesaid application. However, in the case where a light collecting rod is utilized which is wider than the material being examined, e.g. such as shown in U.S. Pat. No. 3,866,054, a simple folded optical arrangement cannot be feasibly implemented. Accordingly, means must be provided for aligning the long light-collecting means positioned adjacent to the material so that the light collecting rod is in alignment with the scanning light beam in order that light variations along the material may be collected along the entire width of material to provide flaw signal information.